This invention relates to a scanning exposure apparatus and a device manufacturing method using the same. More particularly, the invention concerns a scanning exposure apparatus and a device manufacturing method which are suitably usable in a projection exposure step in a photolithographic process for transferring a pattern of a reticle onto a photosensitive substrate by use of a continuous emission excimer laser, which may be used as a light source. Here, the photolithographic process is a process specifically for the manufacture of semiconductor devices such as ICs or LSIs, image pickup devices such as CCDs, display devices such as liquid crystal panels, and magnetic head devices, for example.
In an illumination optical system usable in an exposure apparatus for the manufacture of semiconductor devices, light from a light source may be scanningly deflected by a scanning system to produce a secondary light source, by which a surface to be illuminated, such as a reticle, can be illuminated with light from the secondary light source (Japanese Laid-Open Patent Application, Laid-Open No. 163547/1998).
Scan type projection exposure apparatuses are arranged so that a reticle and a wafer are scanned thereby to transfer a pattern of the reticle onto the wafer, and they have a feature that a wide area of the substrate can be exposed. Examples of such scanning projection exposure apparatuses are disclosed in Japanese Laid-Open Patent Application, Laid-Open Nos. 148241/1997 and 190966/1997.
A continuous emission excimer laser can be used as a light source in the manufacture of semiconductor devices or other devices such as liquid crystal panels, for example, based on the photolithographic technology (Japanese Laid-Open Patent Application, Laid-Open No. 163547/1998). This Japanese patent application document discloses use of an incoherency transforming system in which speckle patterns are removed by use of a rotary diffusion plate provided in an illumination optical system for illuminating a reticle.
However, none of the documents mentioned above specifically considers that: when, for example, a continuous emission excimer laser described above is to be used as a light source in a scan type projection exposure apparatus to scan a pupil plane of an illumination optical system with laser light from the laser to thereby produce a secondary light source of a required shape and size so as to ensure that a reticle is illuminated with light from the secondary light source and a slit-like illumination region is formed thereon, what structure can accomplish accurate projection of the whole reticle pattern on the substrate.
It is accordingly an object of the present invention to provide a scan type exposure apparatus by which, when an illumination system of a pupil plane scanning type is used in a reticle (mask) illuminating optical system of a scanning exposure apparatus, a pattern of the reticle can be transferred onto a substrate very accurately.
In accordance with an aspect of the present invention, there is provided a scanning exposure apparatus, comprising: an illumination optical system for defining an illumination region, having a slit-like section, on an original with the use of laser light; and driving means for relatively scanningly moving an original and a substrate relative to the illumination region, wherein said illumination optical system includes a scanning optical system for scanning a pupil plane of said illumination system with the laser light to produce a secondary light source thereon, such that the illumination region is defined by light from the secondary light source, and wherein, when the width of the illumination region is W (mm), the scan speed of the original and/or the substrate is V (mm/sec), and the time necessary for defining the secondary light source once is T (sec), a relation W=nT is satisfied, where n is an integer.
In accordance with another aspect of the present invention, there is provided a device manufacturing method, comprising the steps of: exposing a substrate with a pattern by use of a scanning exposure apparatus as recited above, and developing the exposed substrate.